The present invention relates to thermosetting resin composition that can be used for adhesive agent requiring low hardening contraction rate, coating agent, paint, injection molding resin, sealing resin used for substrates for mounting electronic parts, solder resist, housing material resin for electric and electronic apparatuses, or the like, and method of manufacturing the inventive thermosetting resin composition.
Recently, relative to down-sizing and thinning of electric and electronic parts, circuit structure has also been thinned. However, varied dimensions of built-in parts may incur unwanted failure such as disconnection or short circuit against extremely thinned circuit structure. Thus, highly precise dimensional stability is required for such material used for electric and electronic parts, and as a result, a greater amount of epoxy resinous thermosetting resin has been used for such thermosetting resin composition available for the above material than that was used in the past.
Epoxy resinous thermosetting resin is basically composed of epoxy resin and an epoxy resin hardening agent. Amines, acid anhydrides, polyamides, imidazoles or isocyanates are used for the epoxy resin hardening agent.
Hardening of epoxy resin is promoted by effect of link-breakage reaction of epoxy link generated by the above-cited epoxy resin hardening agent. Incidentally, since molecules of hardened epoxy resin contain polar hydroxyl radical and ether union, hardened epoxy resin exerts distinguished adhesion to other material with substantial adhesive strength. In addition, hardened epoxy resin also contains outstanding heat resistant property and features less hardening contraction than other thermosetting resins. Nevertheless, even though hardened epoxy resin incurs less hardening contraction than other thermosetting resin, since hardening contraction may be the cause of generating crack inside of hardened epoxy resin or deformation of adhered object, hardened epoxy resin is not suited for such uses requiring highly precise dimensional stability. As a method to deal with such problem caused by hardening contraction of thermosetting resin, filler material is blended in resin. However, this method not only causes smoothness on the surface of resin to be spoiled by blended filler material, but it may also cause proper strength of resin to be lowered. On the other hand, since hardening contraction cannot fully be offset by means of content of filler material within scope of maintaining strength of resin, such problem caused by hardening contraction of thermosetting resin has not yet been solved.
To deal with the above-referred problem caused by hardening contraction of thermosetting resin remaining unsettled in the use of epoxy resin or filler-blended epoxy resin, such a method to solve the above problem by introducing thermosetting resin such as cyanate resin having property to generate expansion via hardening has been conceived. Concretely, this method makes up thermosetting resinous component by means of cyanate resin only, or blend comprising cyanate resin and compound including at least one or more than one of phenolic hydroxyl radical or blend comprising cyanate resin and epoxy resin.
Nevertheless, even when introducing one of the above constituent compositions of thermosetting resin, the following problem is generated. Concretely, when introducing constituent composition of the above cyanate resin alone, it is necessary to execute reaction at a high temperature close to 200.degree. C. to fully terminate hardening of cyanate resin, and thus it is by no means suited for sealing resin or solder resist. On the other hand, when introducing such composition comprising cyanate resin and compound containing at least one or more than one of phenolic hydroxyl radical, although hardening of cyanate resin can be promoted at a temperature lower than the case of solely using cyanate resin, since the above composition is insufficient in adhesive strength, it is not suited for an adhesive agent.
On the other hand, another method is also conceived, which combines epoxy resin exerting strong adhesion with cyanate resin so that properties of both resins in blend can properly be harmonized. This method can indeed provide blend with outstanding heat resistant property and adhesive property. However, since cyanate resin also generates reaction with epoxy resin in addition to own hardening reaction, it results in obstacle to hardening reaction of cyanate resin itself. In consequence, hardening expansion proper to cyanate resin cannot fully be exerted to result in diminished effect of including cyanate resin in constituent composition of thermosetting resin in anticipation of such property as exerting hardening expansion.
Under the above circumstances, in order to fully solve the above problems, inventors followed up researches to provide novel thermosetting resin composition capable of generating distinguished adhesive property, heat resistant property, negligible contraction via hardening, and contributing to achieve high dimensional stability before eventually consummating the invention.